f - S M. The ditches of the Castle of Milan, inside the garland (ghirlanda), are 30 braccia; its embankment is 16 braccia high and 40 wide, and this is the garland. The outer walls are 8 braccia thick and 40 high, and the walls inside the castle are 60 braccia. All of which pleases me, except that I should like to see that the gun-embrasures which are in the walls of the garland do not open onto the secret way within, that is at S; rather that each should be lowered, as appears at M f. For good gunners always aim at the gun-embrasures of fortresses, and if they were to break one single embrasure in the said garland, they could then, by way of sappers (gatti), enter through that breach and make themselves masters of all the towers, walls and secret mines of the said garland. Hence if the embrasures are like M f, and it should happen that a bombard breaks one of them and the enemy enter, they cannot pass any further; rather they will be beaten back and driven off by the machicolation above. And the gallery f must be continued along all the walls from three-quarters down, and from there upward it must have no exit either in the walls or in the towers, save the one by which one enters, which will begin in the keep (rocca). And the said secret way f must have no vent to the outside; rather let it take its light from the side of the keep, through the frequent crossbow-loops.